Microscopic examination of liquid specimens, such as urine, blood, spinal fluid and cell cultures, is usually carried out by placing a small drop of the specimen on a flat transparent microscope slide and then placing a thin flat transparent coverslip over the specimen. The coverslip presses against the slide and spreads the liquid into a thin section or film in the capillary space between the coverslip and the slide. The coverslip-slide combination is then placed on a microscope stage and the thin section of specimen liquid is then microscopically examined through the transparent slide and coverslip.
The above prior art procedure has several disadvantages. First, it requires an excessive amount of manipulation to place the specimen on the slide and then place the coverslip thereon. It requires a certain amount of skill to properly position the coverslip. If an excessive amount of specimen is employed, the excess will be forced out of the capillary space between the slide and coverslip. It is difficult to remove this excess specimen without physically disturbing the position of the coverslip. The entrapment of air between the slide and the coverslip can form undesirable bubbles which interfere with the microscope examination.
Efforts have been made in the prior art to provide liquid specimen holders which overcome the above-described disadvantages of the slide-coverslip combination. Unfortunately, these prior art devices have had problems in use, primarily with formation of undesirable air bubbles in the capillary specimen chamber. Illustrative prior art devices are those shown in U.S. Pat. Nos. 3,565,537 and 3,777,283. There is now a commercial need for a liquid inspection slide that obviates the difficulties of the prior art.